In general, a steam power plant includes a heat source, a steam generator by which steam is generated at multiple pressure levels and heated to a desired superheated level by the heat of the heat source and a system, such as a steam turbine, in which the steam is used for power generation by expansion in the steam turbine.
In such a power plant, steam produced in this manner is transmitted along steam pipelines to the steam turbine. Typically, just upstream of the steam turbine is a main steam control valve (MSCV) located in the steam pipeline. During startup of the steam turbine, the MSCV is kept in a closed condition until the steam in the steam pipeline reaches certain minimum conditions (i.e., minimum temperatures and/or pressures).
Once the minimum conditions are reached, the MSCV is opened and a portion of the steam is permitted to enter the high pressure steam turbine (HPST) where the steam is employed for power generation. The portion of the steam that is not permitted to enter the HPST is diverted to a condenser or to a re-heater of the steam generator by the opening of a bypass valve which is disposed along a bypass line. The steam pipeline has several drain lines provided with drain valves that branch off from it. These drain lines remove steam and/or water that might form by the condensation of steam present in the line during the start up of the power plant.
With this configuration, the time required for the steam to reach the required minimum conditions at the MSCV inlet is relatively long due to improper warming and/or draining of steam pipeline. Therefore, the start up time for the power plant is lengthened. As a result, the overall efficiency of the power plant may be decreased.